1. Field of the invention
The present invention relates to high impact polyvinyl halide compositions and, more particularly, to such polyvinyl halide compositions containing high rubber content acrylonitrile/butadiene/styrene (ABS) copolymers.
2. Background of the Invention
Polyvinyl halide compositions, particularly blends of polyvinyl halides such as polyvinyl chloride (PVC) and styrene based polymers find widespread use in numerous applications. One problem associated with blends of PVC/styrene based polymers is that the presence of the styrene polymers imparts a "glassy" nature to the blends thereby lowering their impact properties. Although impact resistance can be attained by lowering the level of the styrene polymers in the blend, this impacts deleteriously on the heat distortion properties of the blend.
Commercial blends of PVC-containing, styrene based polymers are known. For example, a blend of 45 to 55 percent by weight polyvinyl chloride, 5 to 10 percent by weight of a copolymer of acrylonitrile, butadiene and styrene, 15 to 25 percent by weight of a copolymer of .alpha.-methyl styrene and acrylonitrile, 1 to 10 percent by weight of a copolymer of styrene and acrylonitrile, and 1 to 5 percent by weight of a copolymer of ethylene and vinyl acetate is a commercially available, prior art product. The aforementioned prior art blends, while exhibiting good resistance to heat distortion, suffer from reduced Izod impact strength, particularly at low temperatures.